In recent years, an induction heating cooker which inductively heats a cooking vessel with a heating coil has been appreciated at its excellent characteristics in terms of safety, cleanliness, and high efficiency, and has been in widespread use. An example of such an induction heating cooker is disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 2007-299707).
FIG. 10 is a diagram showing the schematic structure of the conventional induction heating cooker disclosed in Patent Document 1. As shown in FIG. 10, the conventional induction heating cooker includes a top plate 102 on which a cooking vessel 101 being a heating-target object is placed, a heating coil 103 which inductively heats the cooking vessel 101, and an inverter circuit 110 which supplies a high-frequency current to a heating coil 103. Below the heating coil 103, there are disposed an infrared sensor 104 which senses infrared radiation radiated from the cooking vessel 101, and a light emitting portion 105 which is disposed near the infrared sensor 104 to emit light toward the top plate 102.
An output of the infrared sensor 104 is provided to a temperature calculating unit 111. The temperature calculating unit 111 calculates a temperature of the cooking vessel 101 based on such an output signal from the infrared sensor 104. The temperature of the cooking vessel 101 calculated by the temperature calculating unit 111 is provided to a control unit 112. The control unit 112 controls an inverter circuit 110 based on temperature information obtained from the temperature calculating unit 111, to control supply of the high-frequency current to the heating coil 103. The conventional induction heating cooker further includes a pot sensing unit 113 that senses the cooking vessel 101 being placed on the top plate 102 based on an output signal from the inverter circuit 110, a heating operation unit 114 for the user to carry out heating operations with the cooker, and a display unit 115 that displays the operating state of the device.
With the conventional induction heating cooker structured as described above, because the light emitting portion 105 is provided near the infrared sensor 104, the position of the infrared sensor 104 can be reported to the user by allowing the light emitting portion 105 to light up. This makes it possible to guide the user to correctly place the cooking vessel 101 on a region of the top plate 102 above the infrared sensor 104. Further, the output of the infrared sensor 104 changes by the light emitted from the light emitting portion 105 being incident on the infrared sensor 104. Therefore, by sensing whether or not the output of the infrared sensor 104 is equal to or less than a threshold value when the light emitting portion 105 is lit up, it is possible to determine an abnormality (failure) of the infrared sensor 104 before heating the cooking vessel 101. Based on that, the output of the inverter circuit 110 is limited, such that an excessive increase in the temperature of the cooking vessel 101 due to abnormality of the infrared sensor 104 can be avoided.
Patent Document 1: Japanese Unexamined Patent Publication No. 2007-299707